An earlier study purportedly found compositional similarity between raw materials used by modern potters in the northern Valley of Guatemala and Formative period whiteware ceramics from sites in the valley, particularly the major highland center of Kaminaljuyu. The compositional similarity suggested that Formative whiteware was manufactured in the northern valley, and this inference in turn underpinned a model of the development of ceramic craft specialization. Methodological weaknesses in the earlier study cast some doubt on its conclusions. More recent compositional analyses of Formative whiteware indicate that, while whiteware probably was made within the zone from which Kaminaljuyu drew its ceramics, it almost certainly was not made within the northern Valley of Guatemala. The present study highlights some important technical and methodological advances in compositional studies made over the past decade.